Early intervention in COPD.

Much has been learned in the 35 years since the Dutch Hypothesis proposed early identification and intervention in those at risk for COPD. More has been accomplished in identification than in therapy. This is due in part to the powerful addiction of cigarette smoking and the continued search for effective pharmacologic means to prevent the accelerated loss in lung function. The Dutch Hypothesis states that airways hyperresponsiveness predicts future acceleration of the rate of lung function decline, particularly in susceptible smokers. In the Lung Health Study, heightened bronchoconstrictor response to methacholine did, indeed, strongly predict an adverse longitudinal decline in lung function. Further, airway hyperresponsiveness was more common than previously suspected, particularly in women. In this subgroup of cigarette smokers, selected because of early COPD, the incidence of hyperresponsiveness was 62% in men and 87% in women, rather than the anticipated 20%. In addition, in the Lung Health Study data recently released, female continuous smokers with the greatest degree of airway hyperresponsiveness exhibited the fastest rate of decline in lung function. However, cigarette smoking had a greater negative impact than hyperresponsiveness. Those with the greatest responsiveness who quit smoking declined more slowly than those with the least responsiveness who continued to smoke. The evidence continues to mount that smoking cessation should be the first and single most important intervention to prevent COPD. Many studies have demonstrated the beneficial effect of smoking cessation on declining lung function. In the comparison of the randomized groups, the Lung Health Study gives the strongest evidence to date that smoking cessation results in substantial benefit to lung function; the benefit continued to increase during the five year study. There was no evidence in the Lung Health Study that bronchodilator usage prevents the relentless decline in lung function in COPD. The increase of FEV1 among users of ipratroprium (even among the most-compliant) was not sustained when the bronchodilator was discontinued at the end of the study.